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1. Field of the Invention
The present invention relates in general to air filtration systems, and in particular to an air filtration system employable for evacuating smoke generated during a surgical procedure and including a replaceable filter structure thereof provided with filter efficiency measurement selected from (1) a memory device integral with the filter structure and capable of storing and displaying remaining time duration operability data for the filter structure, and (2) a self-contained microprocessor and memory device integral with the filter structure and capable of calculating, storing, and displaying remaining time duration operability data for the filter structure.
2. Background of the Invention
Filtration of airborne contaminants is extremely important where such contaminants have the potential of causing both short-term and long-term health hazards to those who would be exposed to breathing and/or otherwise contacting the untoward components in the air so filtered. One exemplary, but non-limiting, environment where potentially dangerous contaminants may be present is found in a surgical theater where patient tissue is exposed to electro-surgical excision, cauterization, or like heat producing treatments that cause smoke having tissue particulate therewith to emanate from the treatment site and enter the immediate atmosphere. Such particulate can be especially dangerous if its origin is from disease-containing tissue and if that particulate has a tendency to retain disease-transference capabilities.
The necessity for filtration systems to be able to effectively remove airborne particulate, including that found in smoke produced by burning tissue during a surgical procedure, is recognized in the prior art. For example, U.S. Pat. No. 4,810,269 to Stackhouse, et al., U.S. Pat. No. 5,226,939 to Nicolas et al., and U.S. Pat. No. 5,456,248 to Holian et al. all teach variously configured mobile filtration systems capable of removing extremely small particles present in smoke generated during such heat-producing surgical procedures.
At the heart of any filtration system is, of course, the effectiveness of its filter medium. Of particular importance is the ability of any filtration medium to be able to perform adequately in the removal of untoward contaminants. Thus, for example, if a filter medium becomes inundated with particulate, it can become at least partially blocked and therefore may not be adequately efficient in removing potentially toxic particulate. Therefore, it is extremely important that the condition of the filter medium be known when the filtration system with which it is associated is activated so that fully effective particulate removal can occur. One primary indicator that relates to filter medium effectiveness is the cumulative length of time the filter medium has been in use. For example, experience with a particular filter structure may show that such filter structure has a cumulative useful life of about 20 minutes. However, unless the burdensome task of maintaining a written detailed log of operation time is undertaken, a surgical team member must guess an approximation of filtration effectiveness remaining in the filtration system.
While automatic measurement of operating time can be incorporated into system operation, there is yet another factor that also determines filter life and filter efficiency. That factor is the volume of air that has passed through the filter medium. Thus, if the above noted filter is in operation for 20 minutes at a low airflow rate, it may still have filtering capability. Conversely, if the same filter in operation for only 10 minutes at a very high airflow rate, it may not possess proper efficiency.
In view of the above described criticality of filtration efficiency, it is apparent that a need is present for providing immediate filtration capability information in relation to system operation. Accordingly, a primary object of the present invention is to provide correlated cumulative time-sensitive and airflow volume information directly to the user relative to filter structure and remaining life.
Another object of the present invention is to provide such information as a visual display of time remaining for effective use.
Yet another object of the present invention is to provide an audible warning when unacceptable filter medium performance is expected in view of time and airflow volume correlations.
These and other objects of the present invention will become apparent throughout the description thereof which now follows.
The present invention is a filtration system for trapping airborne contaminants wherein operation efficiency thereof is automatically reported in relation to filter structure cumulative use time and airflow volume. An application of use of the system is exemplified in evacuating smoke generated during a surgical procedure such as electrosurgery, cauterization, and the like to thereby entrap potentially hazardous particulate emanating from treated tissue and residing in the smoke. The system includes a housing with an airflow channel therethrough having an air entry port and an air exit port, a vacuum production device for drawing air through the airflow channel, a variable speed motor operating the vacuum production device, and air pressure measuring apparatus disposed at the air entry and air exit ports for measuring air pressure difference between entry and exit ports, and a data display site for displaying remaining time duration operability data. An audible alarm can be included for warning users of untoward filter medium conditions.
In a first preferred embodiment, the system comprises a system processor for receiving and processing data. The system processor is in communication with the variable speed motor for receiving motor speed and operation duration data and in communication with the air pressure measuring apparatus for receiving air pressure difference measurement to thereby correlate cumulative motor speed, operation duration, and air pressure difference measurements into a cumulative time and filtered-air volume operating correlated value and automatically comparing that operating correlated value to a plurality of known pre-determined correlated values each reflecting remaining time duration operability of a replaceable filter structure at one respective pre-determined correlated value. The replaceable filter structure, which is disposed in the airflow channel for capturing airborne contaminants, has at least one filtration medium, and is provided with a memory device in communication with the system processor for receiving and storing remaining time duration operability data and for sending this remaining time duration operability data from the filter structure to the system processor for display at the data display site.
In a second preferred embodiment, the system comprises a filter structure comprising, once again, at least one filtration medium. The filter structure additionally comprises a self-contained microprocessor and memory device in communication with the variable speed motor for receiving motor speed and operation duration data and in communication with the air pressure measuring apparatus for receiving air pressure difference measurement to thereby correlate cumulative motor speed, operation duration, and air pressure difference measurements into an operating cumulative time and filtered-air volume correlated value and automatically comparing that operating correlated value to a plurality of known pre-determined correlated values each reflecting remaining time duration operability of a replaceable filter structure at one respective pre-determined correlated value to determine remaining time duration operability of the filter structure. This remaining time duration operability data is then sent from the microprocessor and memory device of the filter structure to a data display site for display.
The invention includes the filter structure having a memory device only as related in the first preferred embodiment, and the filter structure having a self-contained microprocessor and memory device as related in the second preferred embodiment. As is thus apparent, filtration system efficiency is monitored so that the system can be effective in maintaining a safe operation site.